Abstract 4135: Novel dual A2AA2Badenosine receptor antagonists for cancer immunotherapy: in vitro and in vivo characterization

Design, Synthesis, and Bioevaluation of 2-Aminopteridin-7(8H)-one Derivatives as Novel Potent Adenosine A2A Receptor Antagonists for Cancer Immunotherapy

In recent years, the adenosine A_2A receptor (A_2AR) has shown exciting progress in the development of immunotherapies for the treatment of cancer. Herein, a 2-amino-7,9-dihydro-8H-purin-8-one compound (1) was identified as an A_2AR antagonist hit through in-house library screening. Extensive structure-activity relationship (SAR) studies led to the discovery of 2-aminopteridin-7(8H)-one derivatives, which showed high potencies on A_2AR in the cAMP assay. Compound 57 stood out with an IC₅₀ value of 8.3 ± 0.4 nM against A_2AR at the 5'-N-ethylcarboxamidoadenosine (NECA) level of 40 nM. The antagonistic effect of 57 was sustained even at a higher NECA concentration of 1 μM, which mimicked the adenosine level in the tumor microenvironment (TME). Importantly, 57 enhanced T cell activation in both the IL-2 production assay and the cancer-cell-killing model, thus demonstrating its potential as a lead for developing novel A_2AR antagonists in cancer immunotherapy.

Adenosine A2A Receptor Antagonists for Cancer Immunotherapy

Currently, the most promising therapeutic modality for cancer treatment is the blockade of immune checkpoint pathways, which has revolutionized cancer therapy in the past 15 years. Strategies targeting and modulating adenosine A_2A receptor (A_2AR), an emerging alternative immune checkpoint, have shown the potential to produce significant therapeutic effects. In this review, we describe the immunosuppressive activities of A_2AR and A_2BR in the tumor microenvironment (TME), followed by a summary and discussion of the structure-activity relationship (SAR) of the A_2AR (and dual A_2AR/A_2BR) antagonists that have been experimentally confirmed to exert oncoimmunological effects. This review also provides an update on the compounds under clinical evaluation and insights into the ligand binding modes of the receptor.